Bulletin of The Desert Legume Program of The Boyce Thompson Southwestern Arboretum and The University of Arizona Volume 18, Number 2 August 2006 Legumes of Wallace Desert Gardens Pamela Slate standing relationship between our Desert Gardens reviews and Botanic Coordinator organizations, one I see growing ever approves appropriate on-site Wallace Desert Gardens stronger year after year.” projects of mutual benefit. Wallace Desert Gardens is a Matthew B. Johnson non-profit foundation [(502(c)(3) In the mid-1980’s, the Program Manager and Curator under IRS rules] that was created in Wallace’s moved, complete with their Desert Legume Program 1993, well after much of the garden plant collection, from a Paradise was established. Its mission was Valley acre to a Scottsdale The virtues of desert legumes written by HB, as he was fondly subdivision where they purchased captured the attention of H.B. and known, to reflect the original intent of numerous acre-plus lots. At the time, Jocelyn M. Wallace when they first the foundation: HB had “no idea it would be bigger learned of the Desert Legume than a two-acre garden.” Although Program (DELEP) in 1989, about a Wallace Desert Gardens is a he “knew nothing of desert plants year after the program was founded collection of the world’s deserts when he moved to Arizona” in the at the University of Arizona. They plants located at an elevation of early 1980’s, they quickly became his understood the importance of some 2400 feet. Founded by passion. Today the garden legumes’ potential applications H.B. and Jocelyn M. Wallace in encompasses about eleven acres, worldwide as well as the position of the mid 1980’s, the gardens are having more than 16,000 plants DELEP as a committed champion. home to some twenty-five The resulting alliance between hundred species of which nearly Wallace Desert Gardens (WDG) and half are cacti. Some occupy the DELEP has been, in all aspects, Cactus Pavilion, a 6000-square- mutually beneficial. The Desert foot structure designed by H.B. Legume Program has received Wallace, primarily to protect financial support from Wallace tender species from desert Research Foundation and Mr. and temperatures that drop into the Mrs. Wallace personally. Wallace low twenties. Wallace Desert Desert Gardens became a trial/ Gardens serves its original evaluation garden for interesting and purpose of conserving and unusual species of accessioned protecting plants indigenous to legumes that are today one of its most deserts of the Americas. WDG valuable collections. Mark Bierner, also collects and manages plants Director of Boyce Thompson from other deserts of the world. Arboretum, DELEP’s parent It exemplifies biodiversity in organization, says the WDG legume cultivation and has an interest in collection “is certainly significant for rare and endangered desert botanical reasons. Just as flora. As a supporter of scientific importantly, it exemplifies the long- botanic research, Wallace H.B. Wallace 2 Aridus 18:2 2006 representing over 450 genera and teas and floribundas, in three flower. Their relatively large leaves 2500 species. It is one of the most locations. and flowers and repeat flowering in extensive and extraordinary private In contrast to other botanic spring and fall in shades of pink, make collections found anywhere. Although gardens, WDG has a relatively short them especially appealing for urban HB passed away in August, 2005, he history. However, within that history, desert landscapes. left an enduring botanical legacy for its relationship with DELEP is longer Of interest are the DELEP the use and enjoyment of researchers, and more involved than with any other accession records themselves. For enthusiasts and students alike. botanic organization. The first DELEP example, seed for the Senna aphylla The Living Collection of seedlings were delivered to WDG in was collected in October, 1991 in La Plants (Pg. 7) provides an overview 1990, including Acacia berlandieri, Rioja Province, Argentina. of how the garden is defined. Plants A. constricta, A. eburnea, A. Peltophorum africanum seed came that accompanied the Wallace’s when millefolia,, A. notabilis, A rigidula, from Zimbabwe in July, 1990, they first moved to the property have A. spectabilis, Geoffroea Colutea istria from Israel in July, now reached specimen size, are decorticans, Havardia mexicana, 1989, Acacia cyperophylla from wondrous to all visitors and contribute Havardia pallens, Lucaena retusa, New South Wales, Australia in 1994 significantly to the collections. The Prosopis glandulosa var. and so on. As habitats worldwide are boojum “forest” is a unique mass glandulosa and Prosopis velutina. destroyed, “Botanic gardens play a planting of ten plants grown from seed Since then, legume seedlings have major role in testing new plants and collected under permit in the late been propagated for WDG each serve as storehouses for plant 1970’s. The plants arrived bare root year. diversity,” says WDG Board Member at WDG in the early 1990’s and The Desert Legume Program and botanist Kent Newland. today range in size from about seven supplied seed to several nurseries at The DELEP trial fields at the to twelve feet. All are thriving in soil, about the same time. Seed of other Yuma Mesa Agricultural Center, in climatic and horticultural conditions legumes planted at WDG from 1990 Yuma and the three sites at the U of that are obviously ideal for their to about 1995 can, in some cases, be A Campus Agricultural Center needs. In 2004, WDG acquired its traced through those nurseries back facilities, in Tucson are sites where Ephedra Collection from Stefanie to DELEP, particularly the more performance evaluations have been Ickert-Bond, Ph.D., who collected unusual ones from Australia, South conducted in recent years. All vary and studied the material in preparation America and Africa. Included in this widely in ecological factors – soils, for her dissertation at Arizona State category would be Acacia karroo, temperature, elevation, annual rainfall, University. Unsurpassed in the world, A. saligna, A. visco, Bolusanthus predation, horticultural factors, etc. it is the largest and most complete speciosus, Prosopis tamarugo, Due to a protected site and respresentation of New World Senna purpusii. As the mapping/ horticultural practices of four full-time Ephedra. database projects develop at WDG, staff, legumes at WDG receive The Yucca Collection has efforts will be made to trace DELEP constant nurturing, making them ideal 200 plants representing thirty seed through any of these nursery for evaluation as potential landscape accepted species. Twenty years of records. introductions as well as for legume growth have produced Yucca filifera, Not all horticulturally research. As Kent Newland explains, Y. faxoniana, Y. decipiens, Y. promising legume introductions “All botanic gardens are dependent valida, etc., in sizes upwards of ten originated with DELEP. For example, on collectors for clones of plants in feet, producing an extraordinary floral Mimosa martin-delcampoi was habitat and exist from without rather display for many spring months. originally collected by Ron Gass, than within; we are fortunate indeed Likewise, the Echinopsis collections owner of Mountain States Wholesale to have the interest of Matt Johnson attract neighbors, visitors and Nursery (Litchfield Park, AZ) and and the collections of the Desert professional photographers alike to Greg Starr, botanist and owner of Legume Program.” Beginning this fall, witness and capture the ephemeral, Starr Nursery (Tucson, AZ) near the legumes in the Wallace collection aromatic profusion of color. And no Miquihuana, Tamaulipas, Mexico. will also be evaluated on performance less popular are the Jocelyn M. WDG subsequently tested several using DELEP protocols, providing still Wallace Rose Gardens, a collection plants that have performed so well, another dimension of data to the of two hundred plants, mostly hybrid they captivate all who see them in program. Aridus 18:2 2006 3 trees to 18 ft. tall. The smooth reddish or orange bark contrasts with the foliage that consists of blue-green phyllodes resembling the leaves of some species of Eucalyptus. Yellow flowers in small heads are produced in winter and early spring. Coonavitra wattle appears to be reliably hardy to at least 15° F. It is native to areas of central and southern Australia. Under well-irrigated situations, this species can produce numerous root suckers. Amorpha fruticosa, false indigo, grows as shrubs 6-12 ft. tall. The plants are unarmed, with smooth, tan to gray bark. Leaves are once- pinnate and are winter-deciduous. Attractive, small, dark purple-blue flowers are produced in racemes at the ends of the stems in spring. This species is very cold tolerant. False indigo is widespread in the southwest United States and northern Mexico. Bolusanthus speciosus, tree wisteria, is a graceful, upright, unarmed tree growing 20-30 feet tall. The bark is cinnamon-brown, Acacia cyperophylla becoming deeply furrowed. The glossy green leaves are evergreen unless killed by frost. Beautiful and least 20° F. It is native to arid regions showy blue to mauve flowers are Among the many legumes of Australia. produced in long wisteria-like grown at the Wallace Desert Acacia galpinii, monkey thorn, is a racemes in spring. Cultivated tree Gardens, several species that are large, upright tree with a potential wisteria have survived overnight lows relatively new to Arizona horticulture mature height of 100 ft. though 50 ft. of 20° F without stem damage, have performed particularly well and is more common. Twigs are armed though the foliage is killed at are highlighted below. Several of with viciously sharp, paired, claw-like somewhat higher temperatures. This these were introduced by DELEP. thorns. The pale gray to tan bark tree is native to areas of southeastern Acacia cyperophylla, mineritchie or separates into strips. The foliage is Africa. red mulga, is an unarmed, multiple- gray-green and produces abundant Caesalpinia palmeri, palo piojo, is stemmed shrub or small tree 10-15 ft.